<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title> 波浪边框</title>
</head>
<body>
  <main class="main">
    <div class="wave-border">波浪边框 </div>
  </main>
</body>
</html>